Metal Oxides and Oxysalts as Anode Materials for Li Ion Batteries

Review on recent progress of nanostructured anode materials for Li-ion batteries

This is the first targeted review of the synthesis – microstructure – electrochemical performance relations of MoS2 – based anodes and cathodes for secondary lithium ion batteries (LIBs). Molybdenum disulfide is a highly promising material for LIBs that compensates for its intermediate insertion voltage (∼2 V vs. Li/Li+) with a high reversible capacity (up to 1290 mA h g−1) and an excellent rate capability (e.g. 554 mA h g−1 after 20 cycles at 50 C). Several themes emerge when surveying the scientific literature on the subject: first, we argue that there is excellent data to show that truly nanoscale structures, which often contain a nanodispersed carbon phase, consistently possess superior charge storage capacity and cycling performance. We provide several hypotheses regarding why the measured capacities in such architectures are well above the theoretical predictions of the known MoS2 intercalation and conversion reactions. Second, we highlight the growing microstructural and electrochemical evidence that the layered MoS2 structure does not survive past the initial lithiation cycle, and that subsequently the electrochemically active material is actually elemental sulfur. Third, we show that certain synthesis techniques are consistently demonstrated to be the most promising for battery applications, and describe these in detail. Fourth, we present our selection of synthesis methods that we believe to have a high potential for creating improved MoS2 LIB electrodes, but are yet to be tried.

Lithium ion battery applications of molybdenum disulfide (MoS2) nanocomposites

Detection of hazardous volatile organic compounds (VOCs) by metal oxide nanostructures-based gas sensors: A review

Fe3O4 has long been regarded as a promising anode material for lithium ion battery due to its high theoretical capacity, earth abundance, low cost, and nontoxic properties. However, up to now no effective and scalable method has been realized to overcome the bottleneck of poor cyclability and low rate capability. In this article, we report a bottom-up strategy assisted by atomic layer deposition to graft bicontinuous mesoporous nanostructure Fe3O4 onto three-dimensional graphene foams and directly use the composite as the lithium ion battery anode. This electrode exhibits high reversible capacity and fast charging and discharging capability. A high capacity of 785 mAh/g is achieved at 1C rate and is maintained without decay up to 500 cycles. Moreover, the rate of up to 60C is also demonstrated, rendering a fast discharge potential. To our knowledge, this is the best reported rate performance for Fe3O4 in lithium ion battery to date.

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Three-Dimensional Graphene Foam Supported Fe3O4 Lithium Battery Anodes with Long Cycle Life and High Rate Capability

Crystalline CeO 2 /TiO 2 core/shell nanorods were fabricated by a hydrothermal method and a subsequent annealing process under the hydrogen and air atmosphere. The thickness of the outer shell composed of crystal TiO 2 nanoparticles can be tuned in the range of 5–11 nm. The crystal core/shell nanorods exhibited enhanced gas-sensing properties to ethanol vapor in terms of sensor response and selectivity. The calculated sensor response based on the change of the heterojunction barrier formed at the interface between CeO 2 and TiO 2 is agreed with the experimental results, and thus the change of the heterojunction barrier at different gas atmosphere can be used to explain the enhanced ethanol sensing properties.

Synthesis and enhanced gas sensing properties of crystalline CeO2/TiO2 core/shell nanorods

This paper reported a novel sensing material of porous Ni-doped SnO2 hollow spheres with nanoheterostructures, which were synthesized by a low-cost and environment-friendly hydrothermal strategy. In the process of synthesis, long-chain polymers nickel nitrilotriacetic acid (NiNTA) were formed previously and then successfully heteroconnected with SnO2 through a series of hydrothermal reactions for the reason that nitrilotriacetic acid (NTA) could be dissolved in the aqueous solution of NaSnO3, leading to the complete change of previous morphology. The response of the sensor based on porous Ni-doped SnO2 hollow spheres is up to 59 at 100 ppm ethanol and the detection limit can be dropped to 1 ppm-level, which exhibits enhanced response compared with many ethanol sensors based on pure SnO2 hollow spheres. Such good performance is probably attributed to the formation of p–n junctions between NiO and SnO2, which increase the resistance of sensor and the depletion layers.

Superior ethanol-sensing properties based on Ni-doped SnO2 p–n heterojunction hollow spheres

Crystalline α-MoO 3 /TiO 2 core/shell nanorods are fabricated by a hydrothermal method and subsequent annealing processes under H 2 /Ar flow and in the ambient atmosphere. The shell layer is composed of crystalline TiO 2 particles with a diameter of 2–6 nm, and its thickness can be easily controlled in the range of 15–45 nm. The core/shell nanorods show enhanced sensing properties to ethanol vapor compared to bare α-MoO 3 nanorods. The sensing mechanism is different from that of other one-dimensional metal oxide core/shell nanostructures due to very weak response of TiO 2 nanoparticles to ethanol. The enhanced sensing properties can be explained by the change of type II heterojunction barrier formed at the interface between α-MoO 3 and TiO 2 in the different gas atmosphere. The present results demonstrate a novel sensing mechanism available for gas sensors with high performance.

α-MoO3/TiO2 core/shell nanorods: Controlled-synthesis and low-temperature gas sensing properties

α-Fe2O3 nanowall arrays (NWAs) were grown directly on Ni foam by a facile hydrothermal method. Based on time-dependent experiment results, a possible formation mechanism for this structure was proposed. The as-prepared α-Fe2O3 samples have an open network structure constituted of interconnected nanowalls and can be directly used as integrated electrodes for lithium-ion batteries (LIBs). The unique nanostructural feature is advantageous in electron transport and electrolyte diffusion efficiency, which can accelerate the electrochemical reaction. Thus, compared to a traditional electrode, the unique assembly reduces polarization of the electrode and results in excellent rate performances (440 mA h g−1 at 5 C).

Endi Zhang

Papers

Synthesis and enhanced gas sensing properties of crystalline CeO2/TiO2 core/shell nanorods

Superior ethanol-sensing properties based on Ni-doped SnO2 p–n heterojunction hollow spheres

α-MoO3/TiO2 core/shell nanorods: Controlled-synthesis and low-temperature gas sensing properties

α-Fe2O3 nanowall arrays: hydrothermal preparation, growth mechanism and excellent rate performances for lithium ion batteries

Synthesis of mesoporous SnO2 spheres via self-assembly and superior lithium storage properties